III. Producing Electric Current Ch. 22 - Magnetism III. Producing Electric Current (p.633-639) Electromagnetic Induction Electric Generator DC & AC Transformer 1

A. Electromagnetic Induction producing a current by moving a wire through a magnetic field some microphones work just like mini-speakers in reverse sound waves cause coil to move  current Dynamic Microphone Coil

B. Electric Generator Electric Generator mechanical energy  electrical energy armature is rotated between magnet poles magnetic field induces a current in the wire coil GENERATOR MOTOR

B. Electric Generator Hydroelectric Dam PE of lake water is converted to KE mechanical KE turns the generator shaft which creates electrical energy

C. DC & AC Direct Current (DC) current flows in one direction dry cells Alternating Current (AC) current reverses its direction at regular intervals electrical outlets

D. Transformer Transformer increases or decreases AC voltage primary coil AC produces a magnetic field that induces AC in the secondary coil voltage ratio = ratio of turns in each coil

D. Transformer Step-up Transformer Step-down Transformer increases the voltage more turns power plants Step-down Transformer decreases the voltage fewer turns household appliances (hairdryers, etc.)